Help me solve ; FCC Solving equations

(12 + x)/3 = 5

Multiply each side by 3 :

12 + x = 15

Subtract 12 from each side:

x = 3


x/3 - 5 = 3

Multiply each side by 3 :

x - 15 = 9

Add 15 to each side:

x = 24

At a constant it will take one hour to travel 32 mi.at that speed it will take 1/2 hr to travel the remaining 16 mi.it will take 1+1/2 hr to travel the 48mi @ 32mph.so 1 hr = 60 min& 1/2 hr = 30 min1+1/2 hr = 90 min.there are 60s in each 90 × 60 = 3600 seconds.the real question seriously is he why are they driving so slow? ! lol.