*need asap* can you guys me with these? + 3(-12) ÷ (-3) 2.)if f( n ) = n 2 - n , then f(-4) is - 12 - (-20) 4.)evaluate -2 x 2y , if x = -3 and y = -1.

34m/s;42.5m/s

Step-by-step explanation:

The average speed is defined as:

Distance/ time =1.7km/50 = 1700/50 = 34m/s.

Now let's consider the distance of the journey :

For the first 30s

From Newton's law of motion formula for uniform motion,

S = u × t = k × 30 = 30k

For the last 20s

From Newton's law of motion formula;u -initial velocity , v-final velocity.

S =[ (u + v)/2]t =[( k +0) /2]20 = 10k

Total distance = 30k + 10k = 40k

But 40k =1700

K = 1700/40 = 42.5m/s