Question

15+9=? (5+3) What number is missing from the expression?

Answer 1

`\boxed{ \boxed{ \bold{ \mathsf{3}}}}`

Explanation:

Let the missing number be 'x'

⇒
`\mathsf{15 + 9 = x(5 + 3)}`

Distribute x through the parentheses

⇒
`\mathsf{15 + 9 = 5x + 3x}`

Swap the sides of the equation

⇒
`\mathsf{5x + 3x = 15 + 9}`

Add the numbers

⇒
`\mathsf{5x + 3x = 24}`

Collect like terms

⇒
`\mathsf{8x = 24}`

Divide both sides of the equation by 8

⇒
`\mathsf{ (8x)/(8) = (24)/(8) }`

Calculate

⇒
`\mathsf{x = 3}`

Hope I helped!

Best regards!