Explanation:
1) let n be number of cans
if 1 can has 3 tennis balls, then
n cans will have 3n (n*3) tennis balls.
thus, 3n= 27 (equation)
n=27/3
n=9
2) let the initial temp. be y
y - 5° F = 37 ° F
3) average speed= total distance/ total time
= 40 m / 20 s
= 2 m/s
let me know if there's something you didn't understand, thank you!
-s.