John puts 1250 PSI of oxygen, 780 PSI of Nitrogen and 550 PSI of helium in a SCUBA tank. What is the total pressure?

2580PSI

Explanation:

PSI is also a unit of Pressure and is known as Pounds per square inch.

Total PSI = PSI1 +PSI2+ PSI3

=1250 PSI of oxygen+780 PSI of Nitrogen+550 PSI of helium

= 1250+780+ 550 = 2580PSI

substitute y = 2x - 4 to x + 2y = 12:

x + 2(2x - 4) = 12     use distributive property

x + (2)(2x) + () = 12

x + 4x - 8 = 12     add 8 to both sides

5x = 20     divide both sides by 5

x = 4

put the value of x to the first equation:

y = 2(4) - 4

y = 8 - 4

y = 4