Answer:21
Step-by-step explanation:
Answer:
15.455
Step-by-step explanation:
Answer:
d=-5
Step-by-step explanation:
-4d-37=7d +18
move the terms to its correct side
-4d-7d=18+37
calculate the like terms together.
-11d=55
divide both sides by -11. both of the negavtive (-11) will cancel out and become d on the left and on the right 55 will be divided by -11 = -5. the 5 is negative because there's a negative -11 if there were a postive 11 it will be 5 instead of D=-5
Step-by-step explanation:
The upstream speed is S / t₁, and the downstream speed is S / t₂.
If we say f is the speed of the fish in calm water, and r is the speed of the river, then:
f − r = S / t₁
f + r = S / t₂
If we say T is the time it takes to cross the river, then the speed perpendicular to the river is ℓ/T, the speed parallel to the river is r, and the overall speed is f.
Using Pythagorean theorem:
f² = (ℓ/T)² + r²
f² − r² = (ℓ/T)²
(f − r) (f + r) = (ℓ/T)²
(S / t₁) (S / t₂) = (ℓ/T)²
S² / (t₁ t₂) = (ℓ/T)²
(t₁ t₂) / S² = (T/ℓ)²
√(t₁ t₂) / S = T/ℓ
T = ℓ√(t₁ t₂) / S
Answer:
Sara is now 4, will be 8 in 4 years. Ralph is now 12, will be 16 in 4 years.