Meryl needs to cut down 10.5 trees for every 5 cabins she builds. How many trees will she need to cut to build 3 cabins?

14.7 trees

First you need to find how many trees she cuts down to build one cabin. So you divide:

10.5/5=2.1

She cuts down 2.1 trees to make one cabin.

Next you multiply:

2.1*7=14.7

reduce the friction between its moving parts

step-by-step explanation:

in fact, by reducing the friction between the moving parts of the machine, it is possible to reduce the energy wasted due to this friction; therefore, more input energy is converted into useful work, and this will improve the efficiency of the machine.

9 sandwiches per hour

step-by-step explanation:

when we have a rate, we want a 1 in the denominator

27/3 = 9

27 sandwiches/ 3 hours = 9 sandwiches/hour