X=the units digit
y=the tens digit.
The number is: 10y + x
The reversed number is: 10x+y
The units digit is twice the tens digit, then: x=2y
a)we suggest this system of equations:
x=2y
2(10y+x)=12+(10x+y)
We can solve this system of equations by substitution method:
2(10y+2y)=12+[10(2y)+y]
2(12y)=12+21y
24y=12+21y
24y-21y=12
3y=12
y=12/3
y=4
x=2y
x=2(4)=8
The number is: 10y+x=10*4+8=48
Answer: the number is 48.
b)
the number is: 10x+y
we can suggest this system of equations:
8(x+y)=(10x+y)+19
x=y-2
We can solve this system of equations by substitution method.
8(y-2+y)=[10(y-2)+y]+19
8(2y-2)=11y-20+19
16y-16=11y-1
16y-11y=-1+16
5y=15
y=15/5
y=3
x=y-2
x=3-2=1
The number is: 10x+y=10*1+3=13
Answer:the number is 13.
c)
The number is: 10x+y
The number reversed is: 10y+x
we can suggest this system of equations:
y=2x
2(10x+y)=9+(10y+x)
We solve this system of equations by substitution method:
2(10x+2x)=9+[10(2x)+x]
2(12x)=9+21x
24x=9+21x
24x-21x=9
3x=9
x=9/3
x=3
y=2x
y=2*3=6
The number is: 10x+y=10*3+6=36
Answer: the number is 36
Step-by-step explanation:
3x8=24
24x30=720
720÷18=40 cents
These are vertical angles and if one side is 150 degrees then the other is also 150 degrees so 3x-15=150 so the answer is x =55
10. acute angles: 0
Right angles: 4
Obtuse angles: 0
Perpendicular lines: 0
Parallel lines: 2
11. Acute angles: 2
Right angles: 0
Obtuse angles: 1
Perpendicular lines: 0
Parallel lines: 0
12. H
