Answer:Step-by-step explanation: 4.The solution of the equations is (1,1) Ax+2By = 0 .................................................................(1) 2Ax-4By = 16 ..............................................................(2) Substituting in equation 1 and 2 in (1,1) A+2B = 0 ......................................................................(3) 2A-4B =16 ......................................................................(4) Substitute A=-2B in equation 4 -8B = 16 B = -2 A = -2×-2 = 4 5. We owned an ice-cream shop For 12 double cones you have $24 And want to sell it for $2.50 ∵For 10 double coins wr have to give $25