Iknow the solution of the problem, but the only thing i don't understand is how angle dbc equals 62° (the answer says it's to do with the rule 'angles in the same segment are equal', but how does it actually work in this case? )

See below.

Step-by-step explanation:

M  < DBC = m <  DAC ( because they are both subtended on the circumference by the arc DC).

m < DAC is given as 62 degrees so m <DBC is 62 degrees.

given that triangle abc is transformed two times to get triangle

a"b"c"

first abc is transformed in to a'b'c' as follows:

the coordinates of a are (1,-1) and transformed into a'(-1,1)

similarly b (4,-2) became b'(-4,2) and

c(7,-2) became c'(-7,2)

i.e. (x,y) becomes (-x,-y)

this is nothing but reflection about a point here origin.

thus first transformation is reflection on the origin.

next is exactly shifting 3 units down

source:

c.

step-by-step explanation:

because first you have to add the 4x, 9x, and the 7x together and you get 20x and then you add the last numbers up and you get 5and then you put the subtraction sign in there and that's how you get the answer.