5x + y = 9....multiply by 7
10x - 7y = -18
----------------
35x + 7y = 63 (result of multiplying by 7)
10x - 7y = -18
----------------add
45x = 45
x = 45/45
x = 1
5x + y = 9
5(1) + y = 9
5 + y = 9
y = 9 - 5
y = 4
solution is : (1,4)
=========================
-4x + 9y = 9
x - 3y = -6 ....multiply by 4
----------------
-4x + 9y = 9
4x - 12y = -24 (result of multiplying by 4)
---------------add
- 3y = - 15
y = -15/-3
y = 5
x - 3y = -6
x - 3(5) = -6
x - 15 = -6
x = -6 + 15
x = 9
solution is : (9,5)

is the logical or/disjunction symbol.

means "

or

". Disjunction is commutative, which means

is equivalent to

.
So if

represents

and

represents

, then

means

or

.
Answer:
5
Step-by-step explanation:
20/5 = 5/1
so the answer is c
Answer:
8 yards < 10 yards
He has enough.
Step-by-step explanation:
1 yard = 3 feet
y yards = 24 feet

y · 3 = 1 · 24
3y = 24
3y ÷ 3 = 24 ÷ 3
y = 8
24 feet = 8 yards
8 yards < 10 yards
Alright, so we start off my subtracting 4a from both sides, separating the x and getting 10-4a=2x. Next, we divide both sides by 2, getting that 5-2a=X