Question

If 5A+15=b3 then A+B

Answer 1

5A-3B=15

5A=3B-15

A=3B-15/5

B=5a+15/3

A+B=1

Answer 2

Answer : A + B = 15

Given, 5A + 15 = B3

Since it is given that, B3 instead of 3B. We must understand that, They are the digits of a two digit number rather than terms.

So 5A corresponds to 50 + A

B3 corresponds to 10B + 3.

[ 5 is the tens place digit and A is the units digit for 5A]

[ B is the tens place digit and 3 is the units digit for B3]

Method of solving :

We get a equation like,

50 +A + 15 = 10B + 3

This is not enough to find A + B, or even A & B as it is linear equations in two variables.

Now, We use the fact that, A & B are single digits.

So, Observe the LHS and RHS

5A + 15 = B3

From this, A + 5 = 3

A = - 2 ( Not possible)

But put A = 8,

We will get A + 5 = 13

So,Therefore A = 8

Now, Go back to the equation,

58 + 15 = 73 = B3

So, B = 7.

Therefore, A = 8, B = 7

Finding A + B :

A + B = 8 + 7 = 15

Therefore, A + B = 15