Respuesta :
so pay=hours times pay per hour
so the babysitting job pays 4 dollers pay per hour
she works x hours
therefor the babysitting pay is 4 times x or 4x
the library job pays 7 dollars an hour
she works y hurs
therefor the library pay is 7 times y or 7y
so total pay is babysitting pay plus library pay or
4x+7y=total pay
x+y=total hours
she wants to work no more than 16 hour s aweek, means that she can work max 16 hours or
total hours<16
subsitute
x+y<16
and she wants to earn at least 80 dolars
so more than or equal to 80 dolllars
total pay >80
subsitue
4x+7y>80
so the inequalities we have are
x+y<16 and
4x+7y>80
solve for y since we want to do that
multiply the first equatl by -4
remember tha tmultipy by negative means flip sign from < to > so
-4x-4y>-64
now add to the second equation
-4x-4y>-64
4x+7y>80 +
0x+3y>16
3y>16
divide by 3
y>16/3
16/3=5 and 1/3
so she has to work more than 5 and 1/3 hours per week
basically, she will earn at least 80 dollars a week if she works at least 5 and 1/3 hours at the library and works for 16 hours total (library+babysitting)
what you should do is find the graph of the lines
x+y<16 and 4x+7y>80 and find where they intersect
the inequaltiy is 4x+7y>80 and x+y<16
so the babysitting job pays 4 dollers pay per hour
she works x hours
therefor the babysitting pay is 4 times x or 4x
the library job pays 7 dollars an hour
she works y hurs
therefor the library pay is 7 times y or 7y
so total pay is babysitting pay plus library pay or
4x+7y=total pay
x+y=total hours
she wants to work no more than 16 hour s aweek, means that she can work max 16 hours or
total hours<16
subsitute
x+y<16
and she wants to earn at least 80 dolars
so more than or equal to 80 dolllars
total pay >80
subsitue
4x+7y>80
so the inequalities we have are
x+y<16 and
4x+7y>80
solve for y since we want to do that
multiply the first equatl by -4
remember tha tmultipy by negative means flip sign from < to > so
-4x-4y>-64
now add to the second equation
-4x-4y>-64
4x+7y>80 +
0x+3y>16
3y>16
divide by 3
y>16/3
16/3=5 and 1/3
so she has to work more than 5 and 1/3 hours per week
basically, she will earn at least 80 dollars a week if she works at least 5 and 1/3 hours at the library and works for 16 hours total (library+babysitting)
what you should do is find the graph of the lines
x+y<16 and 4x+7y>80 and find where they intersect
the inequaltiy is 4x+7y>80 and x+y<16