$(-4)^2 - 4 \times 5 =$

$3 - ((-5) - 2) =$

$3 - 4 \times (-5) =$

$30 + (-21) - (+10) + 3 \times 7 =$

$1 + 2 + 3 + 4 + \dots + 29 + 30 =$

$1 - 2 + 3 - 4 + 5 + \dots + 29 + 30 =$

$-2 + 4 - 6 + 8 - 10 + 12 - \dots - 48 + 50 =$

$10 + 11 + 12 + 13 + \dots + 29 =$

$2 + 4 + 6 + 8 + \dots + 20 =$