Question

the sum of two consecutive multiplies of 3 is 69. find them

Answer 1

Let the smaller number be x

so other number is x+3

by the condition given in your question we get equation

x+x+3=69

2x = 66

x=33

x+3=36

so the numbers are 33 & 36

Answer 2

consider the missing number as X now as the question says you have to take consequtive multiples of 3 so the 1st multiple is X+3 and the 2nd one is X+6( as 6 is the second consequtive multiple of 3.