Joe is 20 years old. his sister is half his age less 7. how old is his sister?

i think the answer is 3 but i'm not sure

What is the point-slope form of theequation for the line with a slope of-2 that passes through (1, 4)? a y + 1 = -2(x + 4)b y-1=-2(x-4)c y + 4 = -2(x + 1)d y - 4 = -2(x - 1)

Asmall (but heavy) particle placed in a glass of water will follow a zigzag motion because the particle will bounce off of the water molecules it meets. this is called brownian motion. a physicist simulates this on a computer, by varying the distance a particle can travel (called the mean free length), on average, before it collides with a water molecule and assigning the change in motion to be one of 8 directions, each with a similar probability. by running the simulated particle (with the same mean free length) many times she determines that it should take 15 seconds, on average, for the particle to fall to the bottom, with a standard deviation of 1.5 seconds. next she lets a real particle fall through a glass of water and finds that it took 18 seconds. what does she conclude, and why?

Without multiplying, tell which product is larger and why. 5 × 1/3 or 5 × 2/3 a)5 × 1/3 because 1/3 is less than 2/3 b) 5 × 1/3 because 1/3 is greater than 2/3 c) 5 × 2/3 because 1/3 is less than 23 d) 5 × 23 because 1/3 is greater than 2/3