text: ok i had a maths exam today and i couldnt work out this equation i spent like 20 mins on it can you help? it was   5a+3b=9 and 2a-3b=12  a= b=  it has really been bugging me as i cn work them out a and b have to be the same in each equatuion adding both 7a=21 dividing by 7 a=3 sub in (1) 15+3b=9 adding -15 3b=-6 dividing by 3 b=-2