Question

The sum of two numbers is 39. The second number is 3 more than three times the first number. Let x represent the first number and let y represent the second number. What is the value of the first number? 4 5 6 9

Answer 1

`The\: value \:of\: the\: first\: number\:is\:9`

Explanation:

`We\:have\:a\:system\:of\:equation:\\\left \{ {{x+y=39} \atop {3x+3=y}} \right. \\\Leftrightarrow \left \{ {{39-x=y} \atop {3x+3=39-x}} \right. \\\Leftrightarrow \left \{ {{39-x=y} \atop {4x=36}} \right. \\\Leftrightarrow \left \{ {{y=39-9} \atop {x=9}} \right. \\\Leftrightarrow \left \{ {{y=30} \atop {x=9}} \right. \\\Rightarrow x=9`

Answer 2

Answer with Step-by-step explanation:

The sum of two numbers is 39.

Let x represent the first number and let y represent the second number.

⇒ x+y=39

The second number is 3 more than three times the first number.

⇒ y=3x+3

Putting y=3x+3 in x+y=39

⇒ x+3x+3=39

⇒ 4x=39-3

⇒ 4x=36

Dividing both sides by 4, we get

x=9

Hence, Value of first number is:

9