Question

Answer this question

Answer 1

let the number =x
x/15=7
x=15×7
x= 105

105×3= 315
315/5=63
the reminder =63

Answer 2

Let thr number br A.
By Euclids division lemme, it is clear that,
The number is of form,
A = 15q + 7.
Thrice the number means,
3A = 3 (15q + 7)
= 45q + 21.
= 45q + 20 + 1.

Now the number is divided by 5,
= 5 (9q + 4) + 1.

Clearly , one 1 is the remainder now.

Hope it helps !! ;-)