3s + 135 = 4.5s + 45
Now move the variables and coefficients
135 = 1.5s + 45
And then the numbers
90 = 1.5s
Simplify
90/1.5 = 1.5s/1.5
60 = s
Hope this helps!
F(r) = 3.14r^2....and ur looking for f(5)....so basically all u do is sub in 5 for r.
f(5) = 3.14 * 5^2
f(5) = 3.14 * 25
f(5) = 78.50 <===
