Which ordered pairs lie on the graph of the exponential equation f(x)=128(0.5)^x? select each correct answer. (0, 1) (1, 64) (3, 16) (8, 0.5)

In a two-digit number the units' digit is 7 more than the tens' digit. the number with digits reversed is three times as large as the sum of the original number and the two digits. find the number.