The sum of 2 times x and 5 times y is 7

[math_celebrity]

The sum of 2 times x and 5 times y is 7

2 times x:
2x

5 times y:
5y

The sum of 2 times x and 5 times y:
2x + 5y

The word is means equal to, so we set 2x + 5y equal to 7:
2x + 5y = 7