Explain why adding two multiples of 6 will always result in another multiple of 6

Marlow is comparing the prices of two trucks rental compaines company a charges $3 per hour and an addtional $75 as serivce charges company b charges $2 per hour and an additional $85 as serivce charges

The constant of proportionality is always the where k is the constant of proportionality. additionally, you can find the constant of proportionality by finding the ratio for any point onasap

How many grams the dog will eat in 3 days?