Question

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 I substracted 11 from twice a number , the result was 15 .
(e) Munna substracts 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 .

Answer 1

a) Let $\alpha$ be the number.

According to the statement:

$4+8\alpha =60$

$8\alpha =56$

$\Rightarrow \alpha =7$

b) Let the number be $x$.

According to the statement:

$\frac{1}{5}\times \left(x\right)-4=3$

$\frac{x}{5}=7$

$\Rightarrow x=35$

c) Let the number be $P$.

According to the statement:

$\frac{3}{4}\left(P\right)+3=21$

$\frac{3}{4}\left(P\right)=18$

$\Rightarrow P=6\times 4=24$

d) Let the number be $y$:.

According to the statement.

$2y-11=15$

$2y=26$

$\Rightarrow y=13$

(e) Let the number be $z$.

According to the statement.

$50-3\left(z\right)=8$

$3z=42$

$\Rightarrow z=14$

(f) Let the number that was thought be $k$.

According to the statement:

$\frac{(k+19)}{5}=8$

$k+19=40$

$\Rightarrow k=21$