Search up "math video challenge playbook" and download the file. Go to question number 110 in the Plane Geometry section, I really don't understand what to do.

The perimeter of a triangle is 69 cm. the first is 5 cm shorter than the second side. the third side is twice as long the first side. find the length of each side

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?

Can someone me with my math problem pls my teacher is on my back about this