The amount of balls in a given layer can be found by squaring the layer it is in
4 layers
top layer (1st) is 1
2nd is 4
3rd layer is 9
4th is 16
add them up
1+4+9+16=30
30 in that pyramid
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
Hello,
log base 9(m/(m-4))=-2
==>m/(m-4)=9^(-2)
==>81m=m-4
==>80m=-4
==>m=-1/20
Answer:
5/15
Step-by-step explanation:
Answer:
Point D
Step-by-step explanation:
AD and CD are a line
The intersection of two lines is a point
The two lines intersect at point D
