Answer: 4
Step-by-step explanation:
If there are 13 girls in a class of 23, we can assume there are 10 boys. If 4 girls play chess and there are 10 pupils who play chess, we can guess that the remaining 6 are boys. If there are 10 boys, and 6 of them play chess, there are 4 who do not.
Slope of line perpendicular to ax+by=c is b/a
given
-2x-8y=18
slope of perpendicular is -8/-2=4
y=4x+b
find B
(4,5)
x=4,y=5
5=4(5)+b
5=20+b
minus 20
-15=b
y=4x-15
Answer:
<h2>30</h2>
Step-by-step explanation:
<h3>to understand the steps</h3><h3>you need to know about:</h3>
- system of linear equation
- word problems
- PEMDAS
first step
let's create the equation word problem
<h3>my mother's current age is four times the sum of the ages of my two sisters. After 5 years, my mother's age will be double the sum of the ages of my two sisters. What is the current age of my mother? (imaginary problem)</h3>
let's solve
let my mother's and sister's age be x and y respectively
according to the first condition,x=4y....(I)
according to the 2nd condition,x+5=2(y+5×2).....(ii)
so the system of linear equations is
x=4y
x+5=2(y+5×2)
gets from the second equation
x+5=2(y+10)
x+5=2y+20
4y+5=2y+20 (as x=4y)
2y=15
y=7.5
so the age of mother is
x=4.(7.5)
x=30
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