Algebra: find the value of each variable

Hey, I'm not too quite sure about my answers, but I figured I'd give it a shot.

Let me show you what I did to get my answers.

1. Those little ticks on the triangles means that they're equal. A triangle has a sum of 180 so I took:

2x+2x+40=180

4x+40=180

4x=140

x=35

2. The curves on the sides means that they're also equal so I did:

2x+6=3x-6

2x=3x-12

-x=-12

x=12

4. This is similar to #1. Keep in mind that a right angle has a degree of 90.

5x+5x+90=180

10x+90=180

10x=90

x=9

5. Repeat.

6x+6+6x+6+2x=180

14x+12=180

14x=168

x=12

(n^3 - n)

= n(n-1)(n+1)

since it is divisible by 3 and 2 ,because it is a multiple 3 consecutive number

if, n-1 is odd then n+1 is also odd, then it is a multiple of 9

but if, n-1 is even then n+1 is also even, then it is a multiple of 4

so, largest multiple = max(9*2, 4*3) = max(18, 12) = 18

mr. flanders’ class sold 47 doughnuts and   mr. rodriquez’s class sold 38 cartons of milk

step-by-step explanation:

let x be the number of doughnuts sold by mr. flanders’ class and y be the number of cartons sold by mr. rodriquez’s class.

1. together, the classes sold 85 items, then

x+y=85.

2. both classes earn earned $104.49 for their school. if doughnuts were sold for $1.35 each, then x doughnuts costed $1.35x. if cartons of milk were sold for $1.08 each, then y cartons costed $1.08y. hence,

1.35x+1.08y=104.49.

3. solve the system of two equations: