Please guys help me out with these queries?

[enonem12]

Here is the info:Query 2: Show all orders from London. Display supplier number, part number and quantity.

Query 3: Show the total number of units ordered from each supplier. Display supplier number and total number of units.

Query 4: Show the total weight of parts ordered from each supplier. Display supplier number and total weight.

Query 5: Who supplies the part named “Cam”? Display supplier number and part name.

The necesarry tables:
Table: SUPPLIERS
Suppliers
S_NO SNAME STATUS CITY
S1 Smith 20 London
S2 Jones 10 Paris
S3 Mayrand 30 Paris
S4 Adams 20 London
S5 Stavrulaki 30 Athens
S6 Yuma 20 New York
S7 Singh 10 Bombay

Table: PARTS
Parts
P_NO PNAME Color Unit Price Weight
P1 Nut Red 12 3
P2 Bolt Green 17 9
P3 Screw Blue 17 2
P4 Screw Red 14 2
P5 Cam Blue 12 12
P6 Cog Red 19 10
P7 Plug Black 23 5
P8 Wire Grey 14 2
P9 Washer Black 3 1

Table: ORDERS
Orders
S_NO P_NO Quantity
S1 P2 200
S1 P3 400
S1 P4 200
S1 P5 100
S1 P6 100
S1 P1 300
S2 P1 300
S2 P2 400
S3 P2 200
S3 P9 1200
S4 P4 300
S4 P5 400
S4 P2 200
S5 P9 1000
S5 P4 300
S5 P8 200
S6 P8 800
S6 P1 200
S7 P3 400
S7 P7 600


I've been trying to figure out these esp. the 3 and 4? help.

[enonem12]

for the tables, s_no is supplier number
p_no is part number