How do you simplifly 4x+2y+7+4x+3y

You can simplify this equation by combining like terms.

Like terms are terms with the same variables raised by the same exponents.

For example, 3x and 4x
Both has same variable, x.
Both raised by same exponent, 1.
Therefore, I could add them. 3x+4x=7x

Note: you have 7, which does not have variable or exponent and none other terms are like so. Therefore, you would not add it with any other terms.