A 7th-grade class has 14 girls and 10 boys. An 8th-grade class has 11 girls and 13 boys. What is the probability of picking a st
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Answer: yes , it is possible
Step-by-step explanation:
Let the first number be x and the second number be y .Then , the sum of the two numbers will be x + y , and their difference will be x - y.
Combining the two , we have :
x + y = 1 ............................... equation 1
x - y = 8 ................................. equation 2
solving the system of linear equation by substitution method. From equation 1 , make x the subject of the formula ,
x = 1 - y ...................... equation 3
Substitute equation 3 into equation 2 ,
1 - y - y = 8
1 - 2y = 8
add 2y to both sides
1 = 8 + 2y
subtract 8 from both sides
1 - 8 = 2y
- 7 = 2y
divide through by 2
y =
y = - 3.5
substitute y = -3.5 into equation 3 to find the value of x , we have
x = 1 - y
x = 1 - ( - 3.5 )
x = 1 + 3.5
x = 4.5
Let us check :
x + y will be
4.5 + (-3.5) = 1
Also ,
x - y will be
4.5 - (-3.5)
⇒ 4.5 + 3.5 = 8