How do I solve the following by using substitution?

Y=4x+9

10x=18 - 2y

If a couple has two children, what is the probability that both are boys? assume that it is equally likely that a child is a boy or girl.

Is 10/21 less than or greater than 4/9

What is 1/2x-3/4y=11/60

The top of a glass table is a circle. The circumference is 28.26 ft. What is the radius, and area of the table?

During one month there were 7 days of precipitation. What if there had only been 3 days of precipitation that month? How would that change the measures of center?

The end of the year, Mrs. Weeks bought an assortment of new balls to replace some of the old ones. She had $150.00 to spend. Describe two different ways that Mrs. Weeks could spend her money if she bought at least two of each of the balls.

Which statement explains the relationship between corresponding terms in the table?

What is the answer to this 3 - (|-4|-|-5|)

6. The height of a tent is 6 feet. What is the length of the base of the tent?

Jim earns $9.25 per hour at his part-time job. Which equation represents the amount of money Jim will earn if he works h hours? e=h + $9.25 e = $9.25 h = n - $9.25 e = $9.25 x h