1. make an equation
4x+7(20) = 5(x+20)
2. multiply the numbers and distribute 5 through the parenthesis
4x+140 = 5x+100
3. move variables to the left side and change its sign and move constant to the right side and change its sign
4x-5x = 100-140
4. collect the like terms and calculate the difference
-x = -40
5. change the signs on both sides of the equation
x = 40
he needs to use 40 pounds of the cheaper coffee.
hope this helped!
