Mel's father asked mel to mow his lawn while he was on vacation. mel bought 1.6 gallons of gas for the lawn mower. the gas cost $2.85 per gallon. how much money did mel pay for the gas?

So 1.6*2.85=4.56
here
285              (3(for the decimal)
x 16
1.710
2.850.    See why I put 3?  Since 1.6 has the decimal one place down from the 
4.56.       one's place and 2.85 is 2. Hopefully, you already know how to multiply.

Ifound this on google “that means that the graph of a function with direct variation has these features: it is a straight line: because the slope is the ratio y/x = k. it passes through the origin (0,0): because y = kx = k (0) = 0.” i hope this you for what your looking for