Answer: (a) 9
Step-by-step explanation:
1st multiple of 3: 1(3x)
2nd multiple of 3: 2(3x)
3rd multiple of 3: 3(3x)
Sum = 4(1st multiple of 3) + 6
1(3x) + 2(3x) + 3(3x) = 4(3x) + 6
3x + 6x + 9x = 12x + 6
18x = 12x + 6
6x = 6
x = 1
Largest (3rd) multiple is: 3(3x)
= 9x
= 9 · 1
= 9
