Sonny substituted 5 for x in the proportion 16/x =48/12 and cross multiplied to get 240 = 240. why is this?

16 / 5 = 48 / 12

16 * 12 = 5 * 48
192 = 240

which is incorrect  so 5 cannot be the solution of the equation.

substituting 4 for x  will give you 192=192

I'll do the first one for you. it isn't very hard at all.on number one, you have (50 × 3), which equals 150, and (3 × 3), which equals 9. after you establish that, you add 150 and 9 together. so, (150 + 9) equals 159.this means that 53 × 3 = 159.