Answer:
Jewel is 7 years old
John is 1 year old
Dave is 17 years old
Step-by-step explanation:
From the question we are told that:
Jewel age is 
John age 
Dave's age a Year ago

So that Dave.s age this Year could be

Simplifying Equation for Dave's age we have





Dave is 17 years old
Therefore
Johns age is



John is 1 year old
0.8 times 1200 is 960, which is the number of people when the theatre is 80% full.
Answer:
Love it. My favorite character is probably Elio.
Lets see!
We need to use the pythagorean theorem (a^2+b^2=c^2) to check.
So..
15^2+ 17^2 = 19^2
225+ 289= 361
Hm 225 and 289 do NOT equal 361 therefore it is NOT a right triangle.