Question

cost of one pen and 3 pencil is 29 and 2 pen and 2 pencil is 42 find cost of one pen​

Answer 1

Answer:

According to first sentence, x+3y = 29 -——(1)

According to second sentence, 2x+2y = 42 ---(2)

Equation (1) x 2

2x+6y = 58

2x+2y = 42

----------------- Subtract

4y = 16

y = 4

substitute value of y in equation (1),

x+3y = 29

x+3(4) = 29

x+12 = 29

x = 29-12

x = 17

cost of 1 pen is 17 and 1 pencil is 4

Answer 2

Answer:  

Step-by-step explanation:

Let, Pen=A and Pencil=B

given that, A+3B=29 ............(1)

and 2A+2B=42 ...............(2)

multiplying eqn(1) × 2

we get,             2A+6B=58 ........................(3)

subtracting (3)-(2) we get,

                         2A+6B=58

                         2A+2B=42

                           0+4B=16

                                  B=16/4=4

now by substituting B=4 in (1) we get

               A+3(4)=29

                A=29-12=17

therefore cost of one pen(A)=17