Answer:
Sister = 15 years old
Brother = 12 years old
Step-by-step explanation:
Right now, if the brother is B years old and the sister is S years old, B = (4/5)S because the ratio from brother to sister is 4:5, so if one unit is X, B = 4X and S = 5X
Three years ago, the brother was B-3 years old and the sister was S-3 years old. Keeping one unit as X, we have
B = 3X
S = 4X
B-3 = (3/4)(S-3)
Therefore, we have a system of equations
B = (4/5)S
B-3 = (3/4)(S-3)
Substitute (4/5)S for B into the second equation to only have one variable
(4/5)S - 3 = (3/4)(S-3)
(4/5)S - 3 = (3/4)S - 9/4
add 3 to both sides and subtract (3/4)S from both sides to isolate the variable and its coefficient
(1/20)S = 3/4
multiply both sides by 20 to isolate the S
S = 15
B = (4/5)S = 12
Answer:
B- One-Quarter
Step-by-step explanation:
Answer:
t=1
Step-by-step explanation:
16-2t=t+9+4t
Combine like term
16-2t = 5t+9
Add 2t to each side
16-2t +2t= 5t+2t+9
16 = 7t+9
Subtract 9 from each side
16-9 = 7t+9-9
7 = 7t
Divide each side by 7
7/7 = 7t/7
1=t
Answer:
B
Step-by-step explanation:
Answer:
32
Step-by-step explanation: