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Substitute in the second equation into the first to eliminate x from the first equation. Solve for y which should, when solved (shown below), equal -5. Sub -5 back into either equation in the place of y t...

so we know that A+B+C= 72. We also know that B=2A (1) and C=3B which means C=6A (2) and with this information we can re arrange to equation to be only have one variable. so A+2A+6A= 72 Collecting all the ...

This question is tricky/unfair because you need to understand how meters work. The old reading was the last time the electricity bill was paid for, so the first thing you need to do is 7580-7510= 70. So t...

sub the y value into the first eqn 2x + 3(3x-5) = 18 expand the brackets 2x +9x-15 = 18 add up the x values 11x -15 = 18 a...