Answer:
15
Step-by-step explanation:
Red : Blue :
3 8
We have 40 blue marbles
Multiply 8 by what to get 40
40/8 =5
So we need to multiply by 5
Red : Blue :
3*5 8*5
15 40
There are 15 red marbles
Answer:
482
Step-by-step explanation:
Their 2nd difference is 12
Answer:
25
Step by step:
1. prepare the equation
-4 = x/5 - 9
2. add 9 to both sides
-4 = x/5 - 9
+9 +9
5 = x/5
3. multiply both sides by 5
5 = x/5
(5) (5)
25 = x
4. x=25
Hope this helps
Step-by-step explanation:
Sn= a+[n-1]d
S2= a+[2-1]d
8.5 = a+d _______Equation 1
S5 = a+[5-1]d
13=a+4d ________Equation 2
Subtract Equation 1 from Equation 2
13=a+4d
-
8.5= a+d
________
4.5= 3d
d=1.5
Substituting d=1.5 in equation 1
8.5=a+1.5
a=8.5-1.5
a=7
Sum of terms of an A.P =
Sn= n/2[2a+(n-1)d]
292= n/2[2×7+(n-1)d]
292=n/2[14+(n-1)1.5
292×2=n[14+(n-1)1.5]
584=n[14+1.5n-1.5]
584= 14n+1.5n²-1.5n
584= 1.5n²+12.5n
1.5n²+12.5n-584
1.5n²-24n+36.5n-584
1.5n(n-16)+36.5(n-16)
(1.5n+36.5)(n-16)
**n-16=0
n=16
