Ax+by=z pls help i'm in class

The lengths of all sides of a triangle are integers when measured in decimeters. one of the sides has length of 1 dm and another of 3 dm. find the perimeter of the triangle.'

Cal's go cart has a gas tank with the dimensions shown below. he uses a gas can that holds 11 gallon of gas, to fill the go cart tank. 11 gallon = 231 inches^3 how many full gas cans will it take to fill the go cart's gas tank?

If 5x - 2 = -12, then x = a) -50 b) -4.4 c) -2.8 d) -2