Justin is exchanging dollars for rolls of quarters and rolls of dimes at a bank. each roll of quarters has a value of $10 and each roll of dimes has a value of $5. he exchanges $90 and receives 11 rolls of coins. how many of each type of roll of coins did he receive?

7 roll of quarter and 4 roll of dimes.

Step-by-step explanation:

Let x be the number of rolls of quarters and y be the number of rolls of dimes,

Given,

Total rolls = 11

⇒ x + y = 11 (1),

Also, the total value of $ 90 in which Each roll of quarters has a value of $10 and each roll of dimes has a value of $5.

⇒ 10x + 5y = 90 (2),

Equation (2) - 5 × Equation (1),

We get,

5x = 90 - 55

⇒ 5x = 35 ⇒ x = 7

From equation (1),

7 + y = 11 ⇒ y = 4

Hence, the number of roll of quarters = 7,

And, the number of roll of dimes = 4

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.

77

step-by-step explanation: