Need help with both 6 and 7

Evaluate the expression for the given value of the variable. 5×(h+3) for h=7

Adrawer contains 12 identical white socks, 18 identical black socks and 14 identical brown socks. what is the least number of socks you must choose, without looking, to be certain that you have chosen two socks of the same colour?

Explain how you can use the associative property to evaluate (7x50)x4.