The total number of gifts = x+y.
The inequality is:

Key chains cost $1, Magnets $0.50
Total Cost = x + 0.5y
Inequality is:

Without graphing you can solve system by using substitution:

This is one solution where the maximum x value is given.
So the most keychains that can be purchased is 16. However, because magnets are cheaper, more can be purchased as long as cost remains under 20.
If you solve both inequalities for "y", you get the upper and lower bounds for how many magnets can be purchased given a quantity of keychains.

This is complete solution which gives all possible combinations.
(Graph is Attached)
Answer:
24 quarters and 49 nickels
Step-by-step explanation:
This situation has two unknowns - the total number of nickels and the total number of quarters. Because we have two unknowns, we will write a system of equations with two equations using the two unknowns.
- n+q=73 is an equation representing the total number of coins
- 0.05n+0.25q=8.45 is an equation representing the total value in money based on the number of coin. 0.05 and 0.25 come from the value of a nickel and quarter individually.
We write the first equation in terms of q by subtracting it across the equal sign to get n=73-q. We now substitute this for n in the second equation.
0.05(73-q)+0.25q=8.45
3.65-0.05q+0.25q=8.45
3.65+0.20q=8.45
After simplifying, we subtract 3.65 across and divide by the coefficient of q.
0.20q=4.8
q=24
We now know of the 73 coins that 24 are quarters. To find the number of nickels, we subtract 24 from 73 and get 49 nickels.
<h3>Answer: </h3>
2250 dives
<h3>Explanation</h3>
If each kid dives off the diving board 9 times, for 250 kids, you need to resolve a simple operation:

Answer: 3.5
Step-by-step explanation: Because the 4 and 1 aren’t big enough to change the 5 to go up the final answer would be 3.5 but if the 4 were to be a 5 or a number higher than the 5 would change to a 6.
Calculate the circumference of the full circle:
circumference = PI x diameter = 3.14 x 20 = 62.8 inches
the arc length is 160 degrees of the full circle
divide 160 by 360 (full circle) and multiply by the circumference:
160/360 x 62.8 = 27.9 inches