Answer:
To find the number of nickels and dimes, we can use this equation: 0.10d + 0.05n = 5.25
We are given the information that Sonji has 21 dimes (which means that d=21). We can use the equation to find the number of nickels n.
0.10d + 0.05n = 5.25
0.10(21) + 0.05n = 5.25
2.10 + 0.05n = 5.25
0.05n = 3.15
n = 3.15 / 0.05
n = 315 / 5
n = 63
Sonji has 63 nickels.
Let's check our answer.
21(0.10) + 63(0.05) = 2.10 + 3.15 = 5.25
It seems that our answer is correct.
Step-by-step explanation:
First you had to add by seven from both sides of equation form.

Then simplify by equation.

Next, you multiply by two from both sides of equation form.

And finally, simplify by equation.





Final answer: 
Hope this helps!
And thank you for posting your question at here on brainly, and have a great day.
-Charlie
$5.56/ 453 calories= $0.01227/calorie.
Rounded to the nearest thousandth, the final answer is $0.012/calorie~
Answer:
- Rhombus.
-Trapezoid
Step-by-step explanation: