How to solve 2x+y=8 and 2x-3y=24 by substitution

Jack did 3/5 of all problems on his weekend homework before sunday. on sunday he solved 1/3 of what was left and the last 4 problems. how many problems were assigned for the weekend?

Bring the fraction a/a-4 to a denominator of 16-a^2

Of f(x) is byof f(x)=-3|x| x-.f(x)? a )f(x)=3|x| b) f(x)=|x+3| c) f(x)= -3|x| d) f(x)= -|x+3|