Question

5A + 15 is equal to B3 findA+B

Answer 1

$5a \: + \: 15 = 3b \\ 5a = 3b - 15 \\ a = \frac{3b - 15}{5} .....(1) \\ 5a + 15 = 3b \\ b = \frac{5a + 15}{3} .....(2) \\ putting \: (2) \: in \: (1). \: we \: get \\ a = \frac{5 \times \frac{5a + 15}{3} }{5} \\ a = \frac{5 \times (5a + 15)}{5 \times 3} \\ a = \frac{5a + 15}{3} \\ 3a = 5a + 15 \\ 3a - 5a = 15 \\ - 2a = 15 \\ a = \frac{15}{ - 2} \\ a = - 7.5 \: .....(3) \\ putting \: (3) \: in \: (1) \: we \: get \\ b = \frac{5 \times ( - 7.5) + 15}{3 } \\ b = \frac{ - 37.5 + 15}{3} \\ b = \frac{ - 27.5}{3} \: is \: the \: right \: answer$

Answer 2

Answer:

A+B = 15

Step-by-step explanation:

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