Question

4(x-1)=3(x+1); X(120+130)=1; 24x+21=39(x-6); 3,5x-10=2,5(x+20)

Answer 1

4(x-1)=3(x+1) 
4x-4=3x+3
4x-3x=3+4
x=7

x(1/20+1/30)=1
1/20x+1/30x=1
1/12x=1
x=12