Simplify 3a(2x-7)+5b(7-2x)

$3 a (2 x - 7) + 5 b (7 - 2 x)$

Simplify each term.

Apply the distributive property.

$3 a (2 x) + 3 a \cdot - 7 + 5 b (7 - 2 x)$

Rewrite using the commutative property of multiplication.

$3 \cdot 2 a x + 3 a \cdot - 7 + 5 b (7 - 2 x)$

Multiply $- 7$ by $3$ .

$3 \cdot 2 a x - 21 a + 5 b (7 - 2 x)$

Multiply $3$ by $2$ .

$6 a x - 21 a + 5 b (7 - 2 x)$

Apply the distributive property.

$6 a x - 21 a + 5 b \cdot 7 + 5 b (- 2 x)$

Multiply $7$ by $5$ .

$6 a x - 21 a + 35 b + 5 b (- 2 x)$

Rewrite using the commutative property of multiplication.

$6 a x - 21 a + 35 b + 5 \cdot - 2 b x$

Multiply $5$ by $- 2$ .

$6 a x - 21 a + 35 b - 10 b x$

Reorder.

Move $35 b$ .

$6 a x - 21 a - 10 b x + 35 b$

Move $- 21 a$ .

$6 a x - 10 b x - 21 a + 35 b$