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Q.1 Set up equations and solve them to find the unknown numbers in the following cases:
(a) Add 4 to eight times a number; you get 60.
(b) One-fifth of a number minus 4 gives 3.
(c) If I take three-fourths of a number and add 3 to it, I get 21.
(d) When subtracted 11 from twice a number, the result was 15.
(e) Munna subtracts thrice the number of notebooks he has from 50, he finds the result to be 8.
(f) Ibenhal thinks of a number. If she adds 19 to it and divides the sum by 5, she will get 8.
(g) Anwar thinks of a number. If he takes away 7 from 52 of the numbers, the result is 23.


Answer :

(a) Let the required number be x.
According to question,
8x +4 = 60
= 8x = 60 -4
= x = 56 /8
= x = 7
(b) Let the required number be x.
According to question,
(1/5)x - 4 = 3
= (1/5)x = 3+4
= x = 7 ×5 = 35
= x = 35
(c) Let the required number be x.
According to question,
(3/4)x +3 = 21
= (3/4)x = 21-3
= x = (18 ×4)/3 = 24
= x = 24
(d) Let the required unknown number be x.
According to question,
2x-11= 15
= 2x = 15+11
= x = 26 /2 = 13
= x =13
(e) Let the required number be x. According to question,
50 - 3x = 8
= -3x = 8 - 50
= x = -42 / -3 = 14
= x = 42
(f) Let the required number be x.
According to question,
( x+19)/5=8
= x +19 = 8×5
= x = 40 -19
= x= 21
(g) Let the required number be x.
According to question,
(5/2)x =23 +7
= (5/2)x = 30
= x = (30×2)/5
= x = 12

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