13. A 1 kg mass and 2 kg mass are connected by a string and pass over a smooth pulley as
shown in figure then

i) The acceleration of mass is
(a) 4.66 m/s?
(b) 5.66 m/s?
(c) 6.66 m/s?
(d) 8.76 m/s?
ii) The tension on string is
(a) 8.68 N
(b) 10.68 N
(c) 12.68 N (d) 20.68 N​

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form