7(3a + 12) = 168 ← ( divide both sides by 7 )
3a + 12 = 24 ← ( subtract 12 from both sides )
3a = 12 ← ( divide both sides by 3 )
a = 4
OR
distribute the parenthesis by 7
21a + 84 = 168 ← ( subtract 84 from both sides )
21a = 84 ← ( divide both sides by 21 )
a = 4
Answer:
i have solved them . if u can't understand. .. ask me XD
Answer:
8.8
Step-by-step explanation:
set up a system
let x be sour keys and y be chocolate bars
2.65=15x+2y
3.35=10x+3y
then solve
X turns out to be 0.05
y turns out to be 0.95
multiply : 24*0.05=1.2
multiply : 0.95*8=7.6
add : 1.2+7.6 = 8.8
2 {6 + [12/(3 + 1)]} - 1
2 { 6 + 12/4} - 1
2 { 6 + 3 } - 1
2 {9} - 1
18 - 1
17 <===
