Question

Please help with math! See image below!

Answer 1

`A(b)=10\cdot(b+7)/(2)=5(b+7)=5b+(5)(7)=5b+35\\\\a=5b+35\qquad\text{solve for b}\\\\5b+35=a\qquad\text{subtract 35 from both sides}\\\\5b=a-35\qquad\text{divide both sides by 5}\\\\b=(a)/(5)-(35)/(5)\\\\b=(a)/(5)-7\\\\Answer:\ \boxed{D.\ B(a)=(a)/(5)-7}`