Which expression can be used to model the phrase "the sum of three and a number"? O 3 + x O x minus 3 O 3 minus x O x times 3

Suppose that sahil knows that 45 people with ages of 18 to 29 voted. without using a calculator, he quickly says then 135 people with ages of 30to 49 voted. is he correct? how might sohil have come up with his answer so quickly?

X/y + 4y/x divided by x/y - 2y/x explain as in depth as you can how you simplfied the fractions. i don't know where to start on this : /

Which of the following circles have their centers on the x-axis? check all that apply.