Can someone help me find the value of X and explain step by step ;)

Part a : solve -vp + 40 < 65 for v part b : solve 7w - 3r = 15 for r show your work .

Aformual for 8 bottles of window cleaner calls for 6 cups of rubbing to customers alcohol 2 1/4 gallons of water and 1 1/2 cups of ammonia alcohol would the forula call if a factory made 1,280 bottles for stores to sell to customers

How are algebraic expressions evaluated using substitution?