"solve the following system of linear equations using substitution." y=-6x and 4x+5y=52

You substitute y with -6 and get the equation 4x+5(-6)=52 from there you solve.   
First you do 5 times -6 and get -30 and drop everything else to get 4x+(-30)=52

Second you take the -30 and add 30 to each side to leave you with 4x=82

Third you divide both sides by 4 and that leaves you with x=20.5

So your answer is 20.5 or 20