Given 28p - 36 = 98, find the value of 14p - 19 and 28p - 38. Class 7

Given 28p - 36 = 98, find the value of 14p - 19 and 28p - 38. Class 7

Question 1.

Given 28p - 36 = 98, find the value of 14p - 19 and 28p - 38. Class 7

Solution:

28p - 36 = 98

So, 28p - 36 - 2 = 98 - 2

Hence, 28p - 38 = 96.

Therefore, [latex]\frac {28p-38}{2}[/latex] = [latex]\frac {96}{2}[/latex]

So, 14p - 19 = 48.

Question 2.

The steps to solve three equations are shown below. Identify and correct any mistakes.

(a) 6x + 9 = 66

x + 9 = 11

x = 11 – 9

x = 2

Solution:

(a) Correction in (a)

6x + 9 = 66

6x = 66 - 9 = 57

x = [latex]\frac {57}{6}[/latex] = [latex]\frac {19}{2}[/latex]

(b) 14y + 24 = 36

7y + 12 = 18

7y = 6

y = 6

Solution:

(b) is correct.

(c) 4x - 5 = 9x + 8

4x = 9x + 8 - 5

4x = 9x + 3

4x - 9x = 3

-5x = 3

x = [latex]\frac {-5}{3}[/latex]

Solution:

(c) Correction, in (c)

4x - 5 = 9x + 8 

or 4x - 9x = 8 + 5

or -5x = 13

i.e., x = -[latex]\frac {13}{5}[/latex]