B(2b-4)
b=5
The way to solve a simultaneous equation is to substitute the number value of the given letter into the expression. It then becomes 5(2(5)-4).
you can put this into your calculator or just work it out by hand.
5(2(5)-4)= 30
5x(2x(5)-4)
5x(10-4)
5x(6)
=30