Simplify (6x^2-7x+2)+(15x+5-4x^2)

$(6 x^{2} - 7 x + 2) + (15 x + 5 - 4 x^{2})$

Remove parentheses.

$6 x^{2} - 7 x + 2 + 15 x + 5 - 4 x^{2}$

Subtract $4 x^{2}$ from $6 x^{2}$ .

$2 x^{2} - 7 x + 2 + 15 x + 5$

Add $- 7 x$ and $15 x$ .

$2 x^{2} + 8 x + 2 + 5$

Add $2$ and $5$ .

$2 x^{2} + 8 x + 7$