<span>(13 + 5) + 5 = 23
</span>
associative property of addition
<span>13 + (5 + 5) = 23</span>
Answer:
her first mistake was on line 3.
line 1: 80 + [2(3 1/2 + 1 1/2)]
line 2: 80 + [2(5)]
line 3: 80 + 10
line 4: 90
Step-by-step explanation:
on line 3 she added 80 + 2, but she should have multiplied 2 by 5. the correct steps would be:
line 1: 80 + [2(3 1/2 + 1 1/2)]
line 2: 80 + [2(5)]
line 3: 80 + 10
line 4: 90
You need to have variables one one side and constants on the other. ax - ax + by = c - ax
by = c - ax
by/b = (c - ax)/b
y = (c - ax)/b

so.. as you can see, we use the decimal notation for the percentages... 65% is just 65/100 and 50% is just 50/100 and so on
so.. whatever the salted amounts are, we know they'll add up to (x+175)(0.50)
thus (0.30x) + (175)(0.65) = (x+175)(0.50)
solve for "x"