The weight (in kg) of cubical block of ice 75 cm in length (if one cubic metre of ice weight is 80 kg) is (1) 35

(2) 42.50

(3) 33.75

(4) 40

The weight = 33.75kg

Step-by-step explanation:

Given that  

one cubic metre of ice weight is 80 kg

which is mathematically written as

1m³ of ice = 80 kg

Therefore 75 cm length of  cubical  block of ice =???

First

changing  75 cm to meters, we have  75/100 = 0.75 m

Volume of block = l³= 0.75³ = 0.421875m³

Given that

1m³ = 80kg

0.421875m³=  0.421875 x 80

= 33.75kg

The answer is in the image 

The answer is in the image 

Here,

tip=18%of $32

tip=(18/100)*32

=0.18*32

=$5.76

Total payment=32+5.76=$37.76

The wood before starting =12 feet

Left wood=6 feet

Wood used till now=12-6=6 feet

Picture frame built till now= 6/(3/4)

=8 pieces

Therefore, till now 8 pieces have been made.

The answer is in the image 

30% of 420 are first year students

first year students = (30/100 )*420

=126 students

Student who are not in first year = 420-126

=294 students  

Let the father's age be x and son's be y

10 years before-

Father age=x-10

sons age=y-10

Given,

x-10=10(y-10)

x-10=10y-100

Given present age of father=40

therefore,

x=40

40-10=10y-100

10y-100=30

10y=130

y=130/10

y=13

Therefore present age of son=13years

Given height of gymnasium is 5/6 height of 30 foot ball

therefore height of gymnasium=5/6 * 30

=25 feet