18.
-2(-9)+3
18+3
21
Explanation: -2(-9) When multiplying numbers that have both a negative sign, the answer is positive. Multiply normally.
19.
-6(-4)0
24(0)
0
Explanation: -6(-4) As I explained before, the answer would be positive.
24(0) Every number multiplied by 0 is 0.
20.
56+(-7)
49
Explanation: 56+(-7) Any problem like this is just basically going to be 56-7.
21.
-36+(-4)
-40
Explanation: -36+(-4) You are simply adding normally then adding the sign. This will only work if the signs are the same. (Signs are positive and negative.)
Answer:
...
against the wind, an airplane travels 3640 km in 7 hours.
with the wind, the same plane travels 6000 km in 6hrs.
...
let speed of plane in still air be x mph
speed of wind be y mph.
..
t=d/r
..
against wind speed = x-y mph
with wond speed = x=y mph
...
3640/(x-y)=7
3640 = 7x-7y
/7
520=x-y.....................1
...
6000/x+y = 6
6000 = 6x+6y
/6
1000=x+y.....................2
...
Add (1) & (2)
2x=1520
/2
x=760 mph speed of plane in still air
...
plug value of x in 2
1000=760+y
100-760=y
240 = y
240 mph speed of wind
Answer:
-4
Step-by-step explanation:
g(2) means x=2
