Answer:
(a) [tex]\sf y=\dfrac{11}{20}x+7[/tex]
(b) $16.90
Step-by-step explanation:
Part (a)
Add a line of best fit (see attached).
Find two points on the line: (7, 0) and (20, 18)
Use these points to find the slope of the line:
[tex]\sf slope\:(m)=\dfrac{change\:in\:y}{change\:in\:x}=\dfrac{18-7}{20-0}=\dfrac{11}{20}[/tex]
Use the found slope and one of the points in the point-slope form of the linear equation to find an equation for the line of best fit:
[tex]\sf\implies y-y_1=m(x-x_1)[/tex]
[tex]\sf\implies y-7=\dfrac{11}{20}(x-0)[/tex]
[tex]\sf\implies y=\dfrac{11}{20}x+7[/tex]
Part (b)
Substitute x = 18 into the equation and solve for y:
[tex]\sf\implies y=\dfrac{11}{20}(18)+7=\$16.90[/tex]