Is this ordered pair a solution of the equation?

-2x + y = 4 ( 2 , 7 )

Quick translate "x is 12 units from 20" into an equation. what are the values of x being described? if you can answer any of my other questions that'd be great too

Solve the system of equations. y= 2x y= x^2 - 15

Agarden consists of an apple tree, a pear tree, cauliflowers, and heads of cabbage. there are 40 vegetables in the garden. 24 of them are cauliflowers. what is the ratio of the number of cauliflowers to the number of heads of cabbage?