Arestaurant ordered $900 worth of plates, some of which cost $5 each and some of which cost $10 each. if twice as many $10 plates as $5 plates were ordered, what was the total number of plates ordered?

x is the number of plates which costs $5 and y is the number of $10 plates.

the equation: 5x + 10y = 900 and y=2x

by solving these two equations, x=36 and y= 72, so the total number of plates is 108

its electric no smoke

step-by-step explanation:

you can use a^2+ b^2=c^2