Step-by-step explanation:
3x + 5y = 21 * (-4) •••••• -12x -20y = -84 (a)
4x - 2y = -24 * (3) •••••• 12x -6y = -72 (b)
(a) + (b)
-26y = -156
y = 6
3x + 5 * 6 = 21
3x = 21 - 30
3x = -9
x = -3
<span>The extra cost can be calculated by working out the total he has spent and subtracting the value of the truck. He spends $1500 on a downpayment and (350 x 10 = $3500) on monthly payments, giving him a total outlay of $5000. This means he overspent by $500. $500 interest was paid for 10 months, so at that same rate, $600 would have been paid for 12 months. $600 as a percentage of the cost of the truck minus the down payment ($3000) is 20%. </span>