Https://www.youtube.com/watch?v=WNr31DGrOqw she's explain how to do it without you getting lost because if I told you you'd be lost
The only way to think about this is that the $158 Alberto paid is 70% of the original price. If you save 30% you pay 70% (30% + 70% = 100%)
I will put that into math language
$158 = 70% of n or $158 = .7n Solve by dividing both sides of the equation by .7
(note that when you divide by a decimal less than 1, the answer will be larger than the starting number - $158 - which is exactly what we want.
To the nearest penny the cost of the phone is $225.71
Many people will try to find 30% of $158 and add it onto $158 but that will not work because the 30% came off the unknown price you are looking for and not the $158. You can't find 30% of a price you don't know. You must talk about it in terms of what you a paying - reread the first thing I wrote at the top of this page. You can try the wrong way yourself (finding 30% and adding it on) and when you check it, it won't work.
Answer:5 and 3
So we let the number take the letter b, anc the expression of the question is:
b^2+15=8×b.....so
b^2+15=8b
Then we take the 8b to the other side of the equal sign so that it becomes...
b^2+15-8b=0
Hence it becomes a quadatic equation following the principle ax^2+bx+c where x is the unknown...
From there we work out to get two different numbers...either b-5=0
b=5
Or b-3=0
b=3
So the two numbers are 5 and 3
Answer:
16. 137
17. 89
18. 168
19. 50
20. 8
21. 96
22. 39
23. 5
24. -2
25. 7
Step-by-step explanation:
We have to follow BODMAS which is the acronym for Bracket, Of, Division, Multiplication and Subtraction.
We have to perform our calculations in this order. i.e., Solve the calculations in a bracket first then of and so on.
a = 12; b = 9; c = 4
16. a² + b - c² = (12)² + 9 - 4² = 144 + 9 - 16 = 153 - 16 = 137
17. b² + 2a - c² = 81 + 2(12) - 16 = 81 + 24 - 16 = 105 - 16 = 89
18. 2c(a + b) = 2 · 4 (12 + 9) = 8(21) = 168
19. 4a + 2b - c² = 4(12) + 2(9) - 4² = (48 + 18 - 16 = 66 - 16 = 50
20. [a² ÷ (4b)] + c = [12² ÷ 4(9)] + 4 = [144 ÷ 36] + 4 = 4 + 4 = 8
21. c²(2b - a) = 4²(2(9) - 12) = 4²(18 - 12) = 16(6) = 96
22. [bc² + a] ÷ c = [9(4²) + 12] ÷ 4 = [9(16) + 12] ÷ 4 = 156 ÷ 4 = 39
23. [2c³ - ab] ÷ 4 = [2(4)³ - 12(9)] ÷ 4 = [2(64) - 108] ÷ 4
= [128 - 108] ÷ 4 = 20 ÷ 4 = 5
24. 2(a - b)² - 5c = 2(12 - 9)² - 5(4) = 2(3)² - 20 = 18 - 20 = -2
25. [b² - 2c²] ÷ [a + c - b]
= [9² - 2(4)²] ÷ [12 + 4 - 9] = [81 - 32] ÷ [16 - 9]
= 49 ÷ 7 = 7
Answer:
14
Step-by-step explanation:
14x-y=42
14x=42+y
y=14x-42