8. 4 tins of soup have a mass of 1.8 kg 3 tins of soup and 2 packets of soup have a mass of 1420 g , Find the mass of 7 tins of soup and 5 packets of soup. Give your answer in kiloyrams.

**Step 1: Define the variables** Let \(t\) be the mass of one tin (in kg) and \(p\) be the mass of one packet (in kg). **Step 2: Form the equations** Given that 4 tins have a mass of 1.8 kg, we have: \[ 4t = 1.8 \] Also, given that 3 tins and 2 packets have a mass of 1420 g (which is 1.42 kg), we have: \[ 3t + 2p = 1.42 \] **Step 3: Solve for \(t\)** From the equation for the tins: \[ t = \frac{1.8}{4} = 0.45 \] **Step 4: Solve for \(p\)** Substitute \(t = 0.45\) into the second equation: \[ 3(0.45) + 2p = 1.42 \] Calculate \(3(0.45)\): \[ 1.35 + 2p = 1.42 \] Subtract 1.35 from both sides: \[ 2p = 1.42 - 1.35 = 0.07 \] Solve for \(p\): \[ p = \frac{0.07}{2} = 0.035 \] **Step 5: Find the mass of 7 tins of soup and 5 packets of soup** The total mass \(M\) is given by: \[ M = 7t + 5p \] Substitute \(t = 0.45\) and \(p = 0.035\): \[ M = 7(0.45) + 5(0.035) \] Calculate the masses: \[ 7(0.45) = 3.15 \] \[ 5(0.035) = 0.175 \] Add them together: \[ M = 3.15 + 0.175 = 3.325 \] **Answer:** The mass of 7 tins of soup and 5 packets of soup is \(\boxed{3.325 \text{ kg}}\).