Since you are given a list of choices, you can go through each choice to plug them into the equations. It turns out that choice B is the answer
(3,1) means that a = 3 and b = 1 Plug in a = 3 and b = 1 into the first equation 2a - 5b = 1 2*3 - 5*1 = 1.... replace 'a' with 3, replace b with 1 6 - 5 = 1 1 = 1 we get a true equation, so we have confirmed the first equation
Do the same for the second equation 3a+5b = 14 3*3+5*1 = 14 .... replace 'a' with 3, replace b with 1 9+5 = 14 14 = 14 we get a true equation, so the second equation has been confirmed
Both equations are true when (a,b) = (3,1). So the answer (3,1) has been confirmed fully
Divide 4.10 by 7 to get about 0.59 (round up because you can't get part of a penny) and that gives you 1/8 of a yard's price. Then multiply that by 8 to get a full yard for $4.72.
