Indian soldiers in Siachen glacier brave extreme winters. During November the average temperature is $-35°\mathrm{C}$ which goes up to $-50°\mathrm{C}$ in December. What is the dip in temperature? What value can be learned from this? 

Find the sum of $\left(-7\right)$ and its additive inverse.

Verify that $28\times \left[19+\left(-3\right)\right]=\left[28\times 19\right]+\left[28\times \left(-3\right)\right]$

Simplify using suitable properties.

$\left(-2905\right)\times \left(-98\right)+\left(-2905\right)\times \left(-2\right)$

Simplify using suitable properties:

$\left(1597\times 865\right)-\left(597\times 865\right)$

By what number should I multiply $-6$ to get $-216$?

Simplify $80+\left[240÷\left(-24\right)\right]+8$

What should be added to $\left(-30\right)$ to get $50$?

By what number should $\left(-30\right)$ be divided so that the quotient is $\left(-5\right)$?