The sides of a triangle are in the ratio of 4:5:7 and its perimeter is 64. Find its sides

Ratios are usually good to set up like this:
4x+7x+5x=64 in this case. 4x = the shortest side, 7x = the longest side, and 5x = the middle side. Then solve for x.
16x+64
x=4
Then plug 4 back in for x to see what the individual side lengths are.
4*4=16 for the shortest side.

When rates are expressed as a quantity of 1, such as 2 feet per second or 5 miles per hour, they are called unit rates. if you have a multiple-unit rate such as 120 students for every 3 buses, and want to find the single-unit rate, write a ratio equal to the multiple-unit rate with 1 as the second term.